By Nevin Lawrence
With many acres under prevent plant in the Nebraska Panhandle this year because of drought conditions and delayed water deliveries, a July-planted forage or hay crop is a good option for many growers. Not surprisingly, I have been receiving far more phone calls this year regarding herbicide options for pearl millet. So, what can be used for weed control? Not a lot.
- Preplant burndown options before planting are limited to glyphosate, carfentrazone (AIM®), and paraquat.
- Preemergence (PRE) residual options are limited to mesotrione (Callisto®).
- Postemergence (POST) broadleaf options are limited to 2,4-D and fluroxypyr (Starane®) (only when grown for forage or hay).
Because pearl millet is planted in July, late-emerging weeds are the primary management concern. This includes pigweeds (redroot pigweed and Palmer amaranth), nightshade (hairy, eastern black and buffalobur), and bindweed.
Mesotrione is labeled to control the nightshade and pigweed species commonly found in the Nebraska Panhandle. However, it carries an 18-month rotational restriction for sugarbeet and dry bean and a 10-month restriction for alfalfa, which greatly limits its usefulness depending on the crops planned over the next two years.
Rotation-friendly options include 2,4-D and fluroxypyr, but fluroxypyr controls few of the weeds that would be emerging after the planting of pearl millet. 2,4-D has good activity on bindweed and nightshade. However, Palmer amaranth can quickly outgrow effective control once plants reach 3 to 4 inches tall. Under drought or high-temperature conditions, even smaller plants may be difficult to control.
Source : unl.edu